Showing 1–50 of 163 results for author: Ono, M

Fast Control for LIGO Interferometer Lock Acquisition

Authors: Masaya Ono, Nathan A. Holand, Radhika Bhatt, Peter G. Carney, Francisco Salces Càrcoba, Koji Arai, Rana X. Adhikari

Abstract: Gravitational wave observatories are large scale laser interferometers which are held on resonance to facilitate the detection of gravitational waves. Achieving this resonant condition is a time consuming process, and in the LIGO gravitational-wave observatories this procedure has a relatively low success rate. This limitation leads to a loss of observation time thereby reducing the number of obse… ▽ More Gravitational wave observatories are large scale laser interferometers which are held on resonance to facilitate the detection of gravitational waves. Achieving this resonant condition is a time consuming process, and in the LIGO gravitational-wave observatories this procedure has a relatively low success rate. This limitation leads to a loss of observation time thereby reducing the number of observable astrophysical events. The primary cause of this problem is the coupling among the longitudinal degrees of freedom of the interferometer, particularly the coupling from the arm cavity lengths to the central degrees of freedom, such as the recycling cavities and the Michelson interferometer. We demonstrate a simpler and faster lock acquisition scheme at the 40-meter prototype interferometer, located at the California Institute of Technology. This scheme is achieved by controlling the arm cavity lengths with high bandwidth during the lock acquisition process. In this paper, we describe how this fast lock acquisition is realized, compare it with the current LIGO lock acquisition method, and discuss how our framework can be implemented in LIGO. △ Less

Submitted 19 August, 2026; originally announced August 2026.

Comments: 24 pages, 12 figures, 7 tables

Nanocavity Confinement by Orthogonal Valley- and SSH- Topological Interfaces In Glide-Symmetric Photonic Crystal Structures

Authors: Takahiro Uemura, Wei Dai, Yuto Moritake, Masaaki Ono, Eiichi Kuramochi, Masaya Notomi

Abstract: Valley photonic crystals enable valley-dependent transport and chirality-selective emission, but incorporating wavelength-scale localization remains challenging. Existing valley-photonic-crystal cavities rely on finite defects or local lattice modifications that require structure-specific optimization and offer limited continuous control. Here, we theoretically and experimentally demonstrate two-d… ▽ More Valley photonic crystals enable valley-dependent transport and chirality-selective emission, but incorporating wavelength-scale localization remains challenging. Existing valley-photonic-crystal cavities rely on finite defects or local lattice modifications that require structure-specific optimization and offer limited continuous control. Here, we theoretically and experimentally demonstrate two-dimensional nanocavity confinement using two orthogonal domain walls in a glide-symmetric valley photonic crystal. A valley domain wall confines the guided interface mode transversely, while an SSH-like domain wall localizes it longitudinally. Starting from a glide-symmetry-protected Dirac point in a bearded-interface waveguide, controlled displacements of adjacent triangular holes open a topological gap in the continuous guided-mode dispersion. The displacement amplitude $ΔR$ tunes the gap, mode volume, and intrinsic radiative $Q$ factor. Implemented in a silicon photonic-crystal slab, the structure exhibits localized resonances within the topological mode gap and systematic spectral tuning with $ΔR$. The maximum measured loaded $Q$ factor is $1.2\times10^{4}$. This approach enables continuously tunable, high-$Q$ nanocavities integrated into topological waveguide networks for compact resonant devices and enhanced light--matter interactions. △ Less

Submitted 21 August, 2026; v1 submitted 17 August, 2026; originally announced August 2026.

Comments: 32 pages, 10 figures

Inverse-Designed High-Q/V Silicon Nitride Photonic Crystal Cavities for Second- and Third-Harmonic Generation

Authors: M. Takiguchi, P. Heidt, X. Z. Lim, J. Zöllner, S. Yanagimoto, K. Nakayama, T. Aihara, M. Ono, H. Sumikura, M. Notomi

Abstract: SiN photonic crystal (PhC) cavities are promising platforms for nonlinear and quantum photonics because of their wide transparency window, CMOS compatibility, and negligible two-photon absorption. However, realizing high-Q/V cavities remains challenging because of the relatively low refractive index of SiN. Here, we employ inverse design to optimize a two-dimensional SiN PhC cavity and experimenta… ▽ More SiN photonic crystal (PhC) cavities are promising platforms for nonlinear and quantum photonics because of their wide transparency window, CMOS compatibility, and negligible two-photon absorption. However, realizing high-Q/V cavities remains challenging because of the relatively low refractive index of SiN. Here, we employ inverse design to optimize a two-dimensional SiN PhC cavity and experimentally demonstrate a quality factor of approximately 80,000, the highest reported for a near-stoichiometric SiN 2D PhC cavity. Furthermore, both second- and third-harmonic generation are observed from the same cavity, providing experimental evidence of strong optical confinement and large Q/V. Our results establish inverse-designed SiN PhC cavities as a promising platform for nonlinear photonics and future heterogeneous integrated photonic devices. △ Less

Submitted 13 August, 2026; originally announced August 2026.

Rolling pepper shaker on a slope

Authors: Mizuki Ono, Hirofumi Wada

Abstract: Although the rolling of a solid object is a mundane phenomenon in our daily life, its movement can be surprisingly complex and physically rich, particularly when the solid object has certain internal degrees of freedom, such as a half-filled plastic bottle of water. The translational and rotational motion of such an object couple in a highly nontrivial manner, often leading to seemingly unpredicta… ▽ More Although the rolling of a solid object is a mundane phenomenon in our daily life, its movement can be surprisingly complex and physically rich, particularly when the solid object has certain internal degrees of freedom, such as a half-filled plastic bottle of water. The translational and rotational motion of such an object couple in a highly nontrivial manner, often leading to seemingly unpredictable trajectories. We use a combination of experimental and theoretical approaches to analyze the rolling behaviors of a rigid cylinder that is partially filled with granular media, rolling on an inclined plane. We experimentally find a wide variety of rolling behaviors, including damped oscillation leading to a stop, meandering with avalanches coming to a stop, in addition to the stationary rolling and rolling with a constant acceleration. We address the occurrence of substantial slip during rolling, in contrast to what is often assumed. We classify the rolling behavior into three distinct phases and establish a phase diagram. We theoretically explain the transition between stopping and rolling and rationalize the phase boundary based on the rigid-body mechanics combined with the statics of granular media. Our study addresses the curiosity to understand the everyday phenomena and has significant implications for a wide range of physical applications from powder manufacturing technologies to robotics. △ Less

Submitted 18 July, 2026; originally announced July 2026.

Comments: 9 pages, 10 figures

Planetary Exploration 3.0: A Roadmap for Software-Defined, Radically Adaptive Space Systems

Authors: Masahiro Ono, Daniel Selva, Morgan L. Cable, Marie Ethvignot, Margaret Hansen, Andreas M. Hein, Elena-Sorina Lupu, Zachary Manchester, David Murrow, Chad Pozarycki, Pascal Spino, Amanda Stockton, Mathieu Choukroun, Soon-Jo Chung, John Day, Alexander Demagall, Anthony Freeman, Chloe Gentgen, Michel D. Ingham, Charity M. Phillips-Lander, Richard Rieber, Alejandro Salado, Maria Sakovsky, Lori R. Shiraishi, Yisong Yue , et al. (1 additional authors not shown)

Abstract: The surface and subsurface of worlds beyond Mars remain largely unexplored. Yet these worlds hold keys to fundamental questions in planetary science - from potentially habitable subsurface oceans on icy moons to ancient records preserved in Kuiper Belt objects. NASA's success in Mars exploration was achieved through incrementalism: 22 progressively sophisticated missions over decades. This paradig… ▽ More The surface and subsurface of worlds beyond Mars remain largely unexplored. Yet these worlds hold keys to fundamental questions in planetary science - from potentially habitable subsurface oceans on icy moons to ancient records preserved in Kuiper Belt objects. NASA's success in Mars exploration was achieved through incrementalism: 22 progressively sophisticated missions over decades. This paradigm, which we call Planetary Exploration 2.0 (PE 2.0), is untenable for the outer Solar System, where cruise times of a decade or more make iterative missions infeasible. We propose Planetary Exploration 3.0 (PE 3.0): a paradigm in which unvisited worlds are explored by a single or a few missions with radically adaptive space systems. A PE 3.0 mission conducts both initial exploratory science and follow-on hypothesis-driven science based on its own in situ data returns, evolving spacecraft capabilities to work resiliently in previously unseen environments. The key enabler of PE 3.0 is software-defined space systems (SDSSs) - systems that can adapt their functions at all levels through software updates. This paper presents findings from a Keck Institute for Space Studies (KISS) workshop on PE 3.0, covering: (1) PE 3.0 systems engineering including science definition, architecture, design methods, and verification & validation; (2) software-defined space system technologies including reconfigurable hardware, multi-functionality, and modularity; (3) onboard intelligence including autonomous science, navigation, controls, and embodied AI; and (4) three PE 3.0 mission concepts: a Neptune/Triton smart flyby, an ocean world explorer, and an Oort cloud reconnaissance mission. △ Less

Submitted 21 April, 2026; originally announced April 2026.

Journal ref: AIAA ASCEND 2026

Connections and naïve lifting of DG modules

Authors: Saeed Nasseh, Maiko Ono, Yuji Yoshino

Abstract: In this paper, we generalize the notion of connections, which was introduced by Alain Connes in noncommutative differential geometry, to the differential graded (DG) homological algebra setting. Then, along a DG algebra homomorphism $A \to B$, where $B$ is assumed to be projective as an underlying graded $A$-module, we give necessary and sufficient conditions for a semifree DG $B$-module to be naï… ▽ More In this paper, we generalize the notion of connections, which was introduced by Alain Connes in noncommutative differential geometry, to the differential graded (DG) homological algebra setting. Then, along a DG algebra homomorphism $A \to B$, where $B$ is assumed to be projective as an underlying graded $A$-module, we give necessary and sufficient conditions for a semifree DG $B$-module to be naïvely liftable to $A$ in terms of connections. △ Less

Submitted 18 January, 2026; originally announced January 2026.

Comments: 18 pages

MSC Class: 13N15; 16E45; 16W25; 16W50; 16W80

Semi-fiber products of algebras and lifting of complexes

Authors: Saeed Nasseh, Maiko Ono, Yuji Yoshino

Abstract: Let $k$ be a field. In this paper, we define the notion of semi-fiber products of commutative $k$-algebras and show that the class of such rings contains several classes of commutative rings, including that of the fiber products of local $k$-algebras over their common residue field $k$. For a noetherian local $k$-algebra $R$ and an ideal $I$ of $R$, under certain conditions, we characterize the li… ▽ More Let $k$ be a field. In this paper, we define the notion of semi-fiber products of commutative $k$-algebras and show that the class of such rings contains several classes of commutative rings, including that of the fiber products of local $k$-algebras over their common residue field $k$. For a noetherian local $k$-algebra $R$ and an ideal $I$ of $R$, under certain conditions, we characterize the liftability of $k$ along the natural surjection $R\twoheadrightarrow R/I$ in terms of retractions, sections, and the existence of semi-fiber product decompositions of $R$. △ Less

Submitted 8 January, 2026; originally announced January 2026.

Comments: 12 pages

MSC Class: 13B35; 13D02; 13E05

Low loss switchable topological photonic crystal enabled by submicron-scale patterning and phase-change of Sb2Se3

Authors: Takahiro Uemura, Yuto Moritake, Eiichi Kuramochi, Masaaki Ono, Hisashi Sumikura, Masaya Notomi

Abstract: Photonic topological insulators (PTIs) offer robust platforms for light manipulation, but reconfigurable control of their topological properties without degrading performance remains a major challenge. While phase-change materials (PCMs) provide large refractive index modulation, widely used materials such as Ge2Sb2Te5 (GST) have been successfully deployed in commercial applications including opti… ▽ More Photonic topological insulators (PTIs) offer robust platforms for light manipulation, but reconfigurable control of their topological properties without degrading performance remains a major challenge. While phase-change materials (PCMs) provide large refractive index modulation, widely used materials such as Ge2Sb2Te5 (GST) have been successfully deployed in commercial applications including optical data storage. However, they exhibit significant optical absorption in their crystalline state, which poses a challenge for transmissive photonic devices such as PTIs where high transparency is essential. Here, we overcome this fundamental limitation by integrating the ultra-low-loss PCM antimony triselenide (Sb2Se3) onto a silicon-based 2D PTI. We achieve submicron-scale selective patterning of Sb2Se3 on a photonic crystal for the first time, and demonstrate a topological phase transition induced by the material phase change. Owing to the transparency of Sb2Se3 in both its amorphous and crystalline states, a high Q-factor on the order of 10^3 is preserved-representing nearly an order-of-magnitude improvement over previous GST-based devices. This work resolves the absorption-loss bottleneck in reconfigurable PTIs and paves the way for practical, low-loss, tunable topological photonic devices. △ Less

Submitted 29 December, 2025; originally announced December 2025.

Multi-wavelength Signatures of Supernova Shock Breakout from Red Supergiants in Two Dimensions

Authors: Wun-Yi Chen, Ke-Jung Chen, Keiichi Maeda, Masaomi Ono, Po-Sheng Ou, F. K. Roepke

Abstract: We present new two-dimensional radiation hydrodynamic simulations of supernova shock breakout from red supergiants using the $\texttt{CASTRO}$ code. Our progenitors are 20 and 25 M$_{\odot}$ solar-metallicity stars evolved from the zero-age main sequence with $\texttt{MESA}$ and exploded in one dimension using $\texttt{FLASH}$. We consider a range of circumstellar media (CSM) produced by stellar w… ▽ More We present new two-dimensional radiation hydrodynamic simulations of supernova shock breakout from red supergiants using the $\texttt{CASTRO}$ code. Our progenitors are 20 and 25 M$_{\odot}$ solar-metallicity stars evolved from the zero-age main sequence with $\texttt{MESA}$ and exploded in one dimension using $\texttt{FLASH}$. We consider a range of circumstellar media (CSM) produced by stellar winds to investigate how pre-explosion mass-loss affects shock breakout. The multigroup flux-limited diffusion scheme in $\texttt{CASTRO}$ captures the interaction between the explosion shock, its radiation precursor, and the surrounding CSM. We find that strong radiation precursors, generated by radiation leakage behind the shock, can drive fluid instabilities and move the effective photosphere outward before the shock reaches the stellar surface. The resulting breakout emissions reach peak luminosities of ${\sim}10^{44}$ erg s$^{-1}$ with full-width half-maximum durations of 1-3 hr, , fainter and longer than previous 1D models. The light-curve colors gradually evolve from blue to red after the peak. The 25 M$_{\odot}$ model with explosion energy $E \sim 1.69\times10^{51}$ erg produces ${\sim}$10-30\% higher maximum luminosity than the 20 M$_{\odot}$ model with $E \sim 1.09\times10^{51}$ erg. The dense CSM further extends the breakout rise time by increasing the photon diffusion. These results provide new constraints on red supergiant atmospheres and mass-loss histories prior to core collapse. △ Less

Submitted 28 January, 2026; v1 submitted 8 December, 2025; originally announced December 2025.

Comments: Accepted for publication in ApJ. 21 pages, 8 figures, 2 tables

CEFR-Annotated WordNet: LLM-Based Proficiency-Guided Semantic Database for Language Learning

Authors: Masato Kikuchi, Masatsugu Ono, Toshioki Soga, Tetsu Tanabe, Tadachika Ozono

Abstract: Although WordNet is a valuable resource because of its structured semantic networks and extensive vocabulary, its fine-grained sense distinctions can be challenging for second-language learners. To address this issue, we developed a version of WordNet annotated with the Common European Framework of Reference for Languages (CEFR), integrating its semantic networks with language-proficiency levels.… ▽ More Although WordNet is a valuable resource because of its structured semantic networks and extensive vocabulary, its fine-grained sense distinctions can be challenging for second-language learners. To address this issue, we developed a version of WordNet annotated with the Common European Framework of Reference for Languages (CEFR), integrating its semantic networks with language-proficiency levels. We automated this process using a large language model to measure the semantic similarity between sense definitions in WordNet and entries in the English Vocabulary Profile Online. To validate our approach, we constructed a large-scale corpus containing both sense and CEFR-level information from the annotated WordNet and used it to develop contextual lexical classifiers. Our experiments demonstrate that models fine-tuned on this corpus perform comparably to those fine-tuned on gold-standard annotations. Furthermore, by combining this corpus with the gold-standard data, we developed a practical classifier that achieves a Macro-F1 score of 0.81. This result provides indirect evidence that the transferred labels are largely consistent with the gold-standard levels. The annotated WordNet, corpus, and classifiers are publicly available to help bridge the gap between natural language processing and language education, thereby facilitating more effective and efficient language learning. △ Less

Submitted 11 March, 2026; v1 submitted 21 October, 2025; originally announced October 2025.

Comments: The 15th edition of the Language Resources and Evaluation Conference (LREC 2026); resources are available at https://doi.org/10.5281/zenodo.17395388

Noise-Resilient Quantum Metrology

Authors: Hudson A. Loughlin, Melissa A. Guidry, Jacques Ding, Masaya Ono, Malo Le Gall, Benjamin Lou, Eric Oelker, Xinghui Yin, Vivishek Sudhir, Nergis Mavalvala

Abstract: Quantum metrology seeks to leverage the richness of quantum systems for making better measurements than are possible using only classical resources in order to gain a ``quantum advantage''. Quantum metrology schemes must also be resilient against noise to be useful in practice. Simultaneously achieving quantum advantage and noise resilience requires an end-to-end analysis of quantum measurement sc… ▽ More Quantum metrology seeks to leverage the richness of quantum systems for making better measurements than are possible using only classical resources in order to gain a ``quantum advantage''. Quantum metrology schemes must also be resilient against noise to be useful in practice. Simultaneously achieving quantum advantage and noise resilience requires an end-to-end analysis of quantum measurement schemes to assess their theoretical sensitivity, feasibility, and noise robustness. We demonstrate this approach through the development of a novel optical interferometer based on squeezed vacuum light. We propose a scheme that relies on a nonlinear phase estimation procedure, which allows us to shift the frequency of noise away from the signal band, resulting in a high degree of noise resilience. This enables us to achieve sensitivity with Heisenberg scaling in the lossless limit and sensitivity below the standard quantum limit (SQL) in practice. It also enables the first experimental demonstration of quantum-optimal Bayesian signal estimation in a balanced interferometer. We expect this end-to-end design approach to enable the development of a variety of useful quantum measurement protocols going forward. △ Less

Submitted 5 May, 2026; v1 submitted 29 September, 2025; originally announced September 2025.

Comments: 7+35 pages, 4+11 figures, 0+1 tables

Polywell Revisited

Authors: Jaeyoung Park, Nicholas A. Krall, Giovanni Lapenta, Masayuki Ono

Abstract: The Polywell fusion concept, originally proposed by Robert W. Bussard in 1985, has been investigated for over four decades as a potential solution for achieving net fusion energy in a compact and economically viable reactor. It combines two distinct approaches: high-beta magnetic cusp confinement of electrons using polyhedral coil configurations and electrostatic ion confinement via a potential we… ▽ More The Polywell fusion concept, originally proposed by Robert W. Bussard in 1985, has been investigated for over four decades as a potential solution for achieving net fusion energy in a compact and economically viable reactor. It combines two distinct approaches: high-beta magnetic cusp confinement of electrons using polyhedral coil configurations and electrostatic ion confinement via a potential well formed by injected electron beams. While the hybrid nature of the Polywell system offers advantages in plasma stability and engineering simplicity, previous efforts have been limited by persistent challenges in achieving sufficient plasma confinement required to generate a net energy gain. In this study, we examine previous work and identify limitations of several Polywell embodiments that have historically impeded progress. We present an updated Polywell physics model incorporating experimental findings and recent first-principles particle-in-cell simulations. This updated model outlines a credible path toward overcoming confinement losses and achieving net energy gain using deuterium-tritium (D-T) fuels. Our findings provide a renewed scientific basis for the continued development of the Polywell fusion concept as a practical and scalable approach to fusion energy. △ Less

Submitted 8 August, 2025; originally announced August 2025.

Extreme anisotropies in deep layers of an exploding star: overabundance of Cr in the northeastern jet of Cassiopeia A

Authors: Vincenzo Sapienza, Marco Miceli, Masaomi Ono, Shigehiro Nagataki, Takashi Yoshida, Emanuele Greco, Salvatore Orlando, Fabrizio Bocchino

Abstract: Core-collapse supernovae drive nucleosynthesis under extreme thermodynamic conditions, and complex mechanisms are at work prompting the transport of heavy elements from deep stellar interiors into outer layers. We present spatially resolved X-ray spectroscopy of Cassiopeia A's (Cas A) northeastern (NE) jet using the archival 1 Ms Chandra/ACIS observations, and focusing on three fingers of the jet.… ▽ More Core-collapse supernovae drive nucleosynthesis under extreme thermodynamic conditions, and complex mechanisms are at work prompting the transport of heavy elements from deep stellar interiors into outer layers. We present spatially resolved X-ray spectroscopy of Cassiopeia A's (Cas A) northeastern (NE) jet using the archival 1 Ms Chandra/ACIS observations, and focusing on three fingers of the jet. We report the highest Cr/Fe mass ratio (Cr/Fe $\sim0.14$) ever observed in Cas A, localized in a compact region within the southernmost finger in the NE jet. Comparisons with nucleosynthesis models indicate that the NE jet originated approximately at the boundary separating the complete Si burning layer from the incomplete Si-burning layer. We also find that mixing from different layers is needed to explain the chemical composition of the three fingers in the NE jet. We also detect significant differences in the physical and chemical properties among the three fingers analyzed of the NE jet. In particular, we find that, unlike the other two, the southernmost finger originated from a slightly more peripheral region of the explosion. Moreover, while the northern and central fingers lie almost in the plane of the sky, the southernmost finger is moving in a different direction, showing a velocity along the line of sight of $\sim2100$ km s$^{-1}$ towards the observer, with a tilt angle of $\sim16$\textdegree. These findings highlight the NE jet's role in ejecting material from the deepest explosive burning layers, providing new insights into the asymmetries originating in the inner layers of core-collapse supernovae. △ Less

Submitted 1 August, 2025; originally announced August 2025.

Comments: Accepted for Publication in The Astrophysical Journal Letters, 11 Pages, 4 Figures and 1 Table

Measuring the initial mass of 44Ti in SN 1987A through the 44Sc emission line

Authors: Roberta Giuffrida, Marco Miceli, Emanuele Greco, Salvatore Orlando, Masaomi Ono, Vincenzo Sapienza, Fabrizio Bocchino, Oleh Petruk, Barbara Olmi, Shigehiro Nagataki

Abstract: Context. Deriving the mass and large-scale asymmetries of radioactive isotopes offers valuable insights into the complex phases of a supernova explosion. Important examples are $^{56}$Ni, with its decay products $^{56}$Co and $^{56}$Fe, and $^{44}$Ti, which are studied through their X-rays emission lines and provide a powerful diagnostic tool to probe the explosive nucleosynthesis processes in the… ▽ More Context. Deriving the mass and large-scale asymmetries of radioactive isotopes offers valuable insights into the complex phases of a supernova explosion. Important examples are $^{56}$Ni, with its decay products $^{56}$Co and $^{56}$Fe, and $^{44}$Ti, which are studied through their X-rays emission lines and provide a powerful diagnostic tool to probe the explosive nucleosynthesis processes in the inner layers of the exploding star. Aims. In this framework, SN 1987A provides a privileged laboratory being the youngest supernova remnant from which the mass of Ti has been estimated. However, some tension exists in determining the initial mass of $^{44}$Ti. Previous analysis, relying on \textit{NuSTAR} and \textit{INTEGRAL} data, report $M_{44} = (1.5 \pm 0.3) \times 10^{-4}$ $M_\odot$ and $M_{44}=(3.1 \pm 0.8) \times 10^{-4} M_\odot$, respectively. In this paper we estimate the initial mass of $^{44}$Ti via its decay product, the $^{44}$Sc emission line at 4.09 keV, using \textit{Chandra} observations. Methods. We perform multi-epoch spectral analysis focusing on the inner part of the remnant, to minimize the contamination from the X-ray emission stemming from the shocked plasma. As a result, we provide the detection of $^{44}$Sc emission line in the central part of SN 1987A with a $\sim$99.7\% (3 $σ$) significance. Results. The simultaneous fit of the spectra extracted from observations between 2016 and 2021 provides a line flux of $6.8^{+2.2}_{-2.3}\times 10^{-7}$ photons s$^{-1}$ cm$^{-2}$ corresponding to a $^{44}$Ti mass $M_{44}=(1.6\pm0.5) \times 10^{-4} M_\odot$ (errors at the $90\%$ confidence level). The results obtained with our spectral analysis seem to align with those derived with NuSTAR. △ Less

Submitted 9 July, 2025; originally announced July 2025.

Comments: Accepted in A&A, 6 pages, 4 figures, 5 pages Appendix

Journal ref: A&A 700, A254 (2025)

Tor algebra of local rings with decomposable maximal ideal

Authors: Saeed Nasseh, Maiko Ono, Yuji Yoshino

Abstract: Let $(R,{\frak{m}}_R)$ be a commutative noetherian local ring. Assuming that ${\frak{m}}_R=$$I\oplus J$ is a direct sum decomposition, where $I$ and $J$ are non-zero ideals of $R$, we describe the structure of the Tor algebra of $R$ in terms of the Tor algebras of the rings $R/I$ and $R/J$. Let $(R,{\frak{m}}_R)$ be a commutative noetherian local ring. Assuming that ${\frak{m}}_R=$$I\oplus J$ is a direct sum decomposition, where $I$ and $J$ are non-zero ideals of $R$, we describe the structure of the Tor algebra of $R$ in terms of the Tor algebras of the rings $R/I$ and $R/J$. △ Less

Submitted 16 October, 2025; v1 submitted 2 July, 2025; originally announced July 2025.

Comments: Accepted for publication in Archiv der Mathematik. For the final version see the journal's website

MSC Class: 13D07; 16E30; 16E45

Comparison of simulations and semi-analytical model for WDM subhalo mass functions

Authors: Mizuki Ono, Takashi Okamoto, Shin'ichiro Ando, Tomoaki Ishiyama

Abstract: The Cold Dark Matter (CDM) model successfully explains large-scale structure formation, but challenges remain at smaller scales, leading to interest in Warm Dark Matter (WDM) as an alternative. The abundance of Milky Way subhalos depends on the mass of WDM particles, allowing constraints to be obtained by comparing observations and theoretical models. However, high-resolution simulations of heavie… ▽ More The Cold Dark Matter (CDM) model successfully explains large-scale structure formation, but challenges remain at smaller scales, leading to interest in Warm Dark Matter (WDM) as an alternative. The abundance of Milky Way subhalos depends on the mass of WDM particles, allowing constraints to be obtained by comparing observations and theoretical models. However, high-resolution simulations of heavier WDM particle masses are computationally demanding, making semi-analytical approaches valuable. In this study, we evaluate the ability of the Semi-Analytical Sub-Halo Inference Modeling for WDM (SASHIMI-W) to reproduce subhalo mass functions for heavier WDM particle masses. We perform high-resolution cosmological N-body simulations for CDM and WDM with particle masses of 1 keV, 3 keV, and 10 keV, and compare the ratio of the subhalo mass function between WDM and CDM cases. Our results show that SASHIMI-W successfully reproduces the simulation results over redshifts z = 0 to z = 2. Furthermore, both simulations and the semi-analytical model show a slight redshift dependence in the subhalo suppression ratio. However, a direct comparison of the differential subhalo mass functions shows discrepancies in the mid- and low-mass regions, suggesting that the tidal stripping effects implemented in SASHIMI-W may be too strong for WDM subhalos, or that the removal of spurious subhalos in the simulations is insufficient. These results validate the use of SASHIMI-W in constraining WDM properties, and highlight the need for refinements in both tidal effect modeling and spurious subhalo filtering to improve subhalo abundance predictions. △ Less

Submitted 22 August, 2025; v1 submitted 21 May, 2025; originally announced May 2025.

Comments: 10 pages, 6 figures. Accepted for publication in PASJ. Updated to match the version accepted by the journal after minor revisions

Tracing the ejecta structure of SN 1987A: Insights and diagnostics from 3D MHD simulations

Authors: S. Orlando, M. Miceli, M. Ono, S. Nagataki, M. -A. Aloy, F. Bocchino, M. Gabler, B. Giudici, R. Giuffrida, E. Greco, G. La Malfa, S. -H. Lee, M. Obergaulinger, O. Petruk, V. Sapienza, S. Ustamujic, J. Weng

Abstract: Supernova (SN) 1987A provides a unique window into the aftermath of a massive stellar explosion, offering key insights into the ejecta's morphology, composition, explosion mechanism, progenitor system, and circumstellar medium (CSM) interaction. We investigate large-scale ejecta asymmetries in SN 1987A. By comparing the simulations with JWST observations and making predictions for XRISM, we aim to… ▽ More Supernova (SN) 1987A provides a unique window into the aftermath of a massive stellar explosion, offering key insights into the ejecta's morphology, composition, explosion mechanism, progenitor system, and circumstellar medium (CSM) interaction. We investigate large-scale ejecta asymmetries in SN 1987A. By comparing the simulations with JWST observations and making predictions for XRISM, we aim to refine our understanding of the explosion mechanism and the remnant's evolution. We performed 3D MHD simulations that trace the evolution of SN 1987A from the SN to the SNR, extending our predictions up to 5000 years into the future and considering the Ni-bubble effects. The simulation results are compared with JWST observations and used to predict XRISM spectra, to evaluate the accuracy of the modeled ejecta structure. Our simulations reproduce the large-scale Fe-rich ejecta morphology seen by JWST, revealing two clumps suggestive of a bipolar explosion. Ni-bubble effects in the first year boost Fe-rich ejecta expansion and their interaction with the reverse shock. However, discrepancies with JWST observations in clump velocities and spatial distribution suggest stronger explosion asymmetries than modeled. Since 2021, our models predict that shocked ejecta have contributed increasingly to X-ray emission, now rivaling shocked CSM and soon dominating as the latter fades. Future XRISM observations will trace the evolution of these ejecta structures, refining constraints on explosion geometry. Early remnant asymmetries from CSM interaction may persist for at least 100 years. Our results underscore the role of asymmetric core-collapse mechanisms in shaping SN 1987A's ejecta and constraining its explosion geometry. Future studies should explore more extreme asymmetries, in neutrino-driven core collapse or magneto-rotational SN models, to identify the origin of its bipolar Fe-rich structure. △ Less

Submitted 28 April, 2025; originally announced April 2025.

Comments: The manuscript consists of 24 pages and 16 figures

Journal ref: A&A 699, A305 (2025)

Origin of holes and rings in the Green Monster of Cassiopeia A: Insights from 3D magnetohydrodynamic simulations

Authors: S. Orlando, H. -T. Janka, A. Wongwathanarat, F. Bocchino, I. De Looze, D. Milisavljevic, M. Miceli, T. Temim, J. Rho, S. Nagataki, M. Ono, V. Sapienza, E. Greco

Abstract: [Abridged] Cassiopeia A (Cas A) provides a unique opportunity to study supernova (SN) dynamics and interactions with the circumstellar medium (CSM). Recent JWST observations revealed the "Green Monster" (GM), a structure with a likely CSM origin. We investigate its pockmarked morphology, characterized by circular holes and rings, by examining the role of small-scale ejecta structures interacting w… ▽ More [Abridged] Cassiopeia A (Cas A) provides a unique opportunity to study supernova (SN) dynamics and interactions with the circumstellar medium (CSM). Recent JWST observations revealed the "Green Monster" (GM), a structure with a likely CSM origin. We investigate its pockmarked morphology, characterized by circular holes and rings, by examining the role of small-scale ejecta structures interacting with a dense circumstellar shell. We adopted a neutrino-driven SN model to trace the evolution of its explosion from core collapse to the age of the Cas A remnant using high-resolution 3D magnetohydrodynamic simulations. Besides other processes, the simulations include self-consistent calculations of radiative losses, accounting for deviations from electron-proton temperature equilibration and ionization equilibrium, as well as the ejecta composition derived from the SN. The GM's morphology is reproduced by dense ejecta clumps and fingers interacting with an asymmetric, forward-shocked circumstellar shell. The clumps and fingers form by hydrodynamic instabilities growing at the interface between SN ejecta and shocked CSM. Radiative cooling accounting for effects of non-equilibrium of ionization enhances the ejecta fragmentation, forming dense knots and thin filamentary structures that penetrate the shell, producing a network of holes and rings with properties similar to those observed. The origin of the holes and rings in the GM can be attributed to the interaction of ejecta with a shocked circumstellar shell. By constraining the timing of this interaction and analyzing the properties of these structures, we provide a distinction of this scenario from an alternative hypothesis, which attributes these features to fast-moving ejecta knots penetrating the shell ahead of the forward shock. △ Less

Submitted 18 March, 2025; originally announced March 2025.

Comments: The manuscript consists of 17 pages, 11 figures, 2 Appendices, 2 online movies, and 3 interactive graphics

Risk-aware Integrated Task and Motion Planning for Versatile Snake Robots under Localization Failures

Authors: Ashkan Jasour, Guglielmo Daddi, Masafumi Endo, Tiago S. Vaquero, Michael Paton, Marlin P. Strub, Sabrina Corpino, Michel Ingham, Masahiro Ono, Rohan Thakker

Abstract: Snake robots enable mobility through extreme terrains and confined environments in terrestrial and space applications. However, robust perception and localization for snake robots remain an open challenge due to the proximity of the sensor payload to the ground coupled with a limited field of view. To address this issue, we propose Blind-motion with Intermittently Scheduled Scans (BLISS) which com… ▽ More Snake robots enable mobility through extreme terrains and confined environments in terrestrial and space applications. However, robust perception and localization for snake robots remain an open challenge due to the proximity of the sensor payload to the ground coupled with a limited field of view. To address this issue, we propose Blind-motion with Intermittently Scheduled Scans (BLISS) which combines proprioception-only mobility with intermittent scans to be resilient against both localization failures and collision risks. BLISS is formulated as an integrated Task and Motion Planning (TAMP) problem that leads to a Chance-Constrained Hybrid Partially Observable Markov Decision Process (CC-HPOMDP), known to be computationally intractable due to the curse of history. Our novelty lies in reformulating CC-HPOMDP as a tractable, convex Mixed Integer Linear Program. This allows us to solve BLISS-TAMP significantly faster and jointly derive optimal task-motion plans. Simulations and hardware experiments on the EELS snake robot show our method achieves over an order of magnitude computational improvement compared to state-of-the-art POMDP planners and $>$ 50\% better navigation time optimality versus classical two-stage planners. △ Less

Submitted 26 February, 2025; originally announced February 2025.

Comments: 8 pages, 9 figures. Accepted article with supplemental material for presentation at the 2025 IEEE International Conference on Robotics and Automation (ICRA)

ACM Class: I.2.8; I.2.9

TockyLocus: Quantitative Analysis Methods for Flow Cytometric Fluorescent Timer Data

Authors: Masahiro Ono

Abstract: Fluorescent Timer proteins, which spontaneously change their emission spectra over time, are valuable tools for analyzing temporal changes in cellular activities at the single-cell level. Traditional analysis of Fluorescent Timer data has mostly relied on conventional flow cytometric methods, which lacks the sophistication needed for detailed quantitative analysis. Recently, we developed the Timer… ▽ More Fluorescent Timer proteins, which spontaneously change their emission spectra over time, are valuable tools for analyzing temporal changes in cellular activities at the single-cell level. Traditional analysis of Fluorescent Timer data has mostly relied on conventional flow cytometric methods, which lacks the sophistication needed for detailed quantitative analysis. Recently, we developed the Timer-of-Cell-Kinetics-and-Activity (Tocky) tools, employing transgenic reporter systems using an mCherry mutant Timer protein, Fast-FT, to analyze these changes, implementing data preprocessing methods for Timer fluorescence. Despite this advancement, the computational implementation of effective quantitative analysis methods for Fluorescent Timer data has been lacking. In this study, we introduce rigorous algorithms for a data categorization method, designated as the Tocky locus approach, which uses normalized and trigonometric-transformed Fluorescent Timer data, suitable for quantitative analysis. We found that the five-locus approach, which categorizes Timer fluorescence into five categories, optimally captures the dynamics of Timer profiles, thus enabling effective quantitative statistical analysis and biological interpretation. The current study has developed comprehensive tools for data categorization, visualization, and statistical analysis optimized to Tocky Locus data. These algorithms have been implemented in the TockyLocus package, a new R package designed to facilitate the quantitative analysis of Timer fluorescence data. This toolkit is expected to significantly enhance the utility of experimental systems using Fluorescent Timer proteins, particularly the Tocky tools, by standardizing methods for analyzing dynamic cellular events and responses. △ Less

Submitted 14 November, 2024; originally announced November 2024.

Comments: 31 pages, 15 figures

TockyPrep: Data Preprocessing Methods for Flow Cytometric Fluorescent Timer Analysis

Authors: Masahiro Ono

Abstract: Background: Fluorescent Timer proteins, which display time-dependent changes in their emission spectra, are invaluable for analyzing the temporal dynamics of cellular events at the single-cell level. We previously developed the Timer-of-cell-kinetics-and-activity (Tocky) tools, utilizing a specific Timer protein, Fast-FT, to monitor temporal changes in cellular activities. Despite their potential,… ▽ More Background: Fluorescent Timer proteins, which display time-dependent changes in their emission spectra, are invaluable for analyzing the temporal dynamics of cellular events at the single-cell level. We previously developed the Timer-of-cell-kinetics-and-activity (Tocky) tools, utilizing a specific Timer protein, Fast-FT, to monitor temporal changes in cellular activities. Despite their potential, the analysis of Timer fluorescence in flow cytometry is frequently compromised by variability in instrument settings and the absence of standardized preprocessing methods. The development and implementation of effective data preprocessing methods remain to be achieved. Results: In this study, we introduce the R package that automates the data preprocessing of Timer fluorescence data from flow cytometry experiments for quantitative analysis at single-cell level. Our aim is to standardize Timer data analysis to enhance reproducibility and accuracy across different experimental setups. The package includes a trigonometric transformation method to elucidate the dynamics of Fluorescent Timer proteins. We have identified the normalization of immature and mature Timer fluorescence data as essential for robust analysis, clarifying how this normalization affects the analysis of Timer maturation. These preprocessing methods are all encapsulated within the TockyPrep R package. Conclusions: TockyPrep is available for distribution via GitHub at https://github.com/MonoTockyLab/TockyPrep, providing tools for data preprocessing and basic visualization of Timer fluorescence data. This toolkit is expected to enhance the utility of experimental systems utilizing Fluorescent Timer proteins, including the Tocky tools. △ Less

Submitted 29 June, 2025; v1 submitted 6 November, 2024; originally announced November 2024.

Comments: 24 pages, 11 figures

Journal ref: BMC Bioinformatics 26, 44 (2025)

GatingTree: Pathfinding Analysis of Group-Specific Effects in Cytometry Data

Authors: Masahiro Ono

Abstract: Advancements in cytometry technologies have led to a remarkable increase in the number of markers that can be analyzed simultaneously, presenting significant challenges in data analysis. Traditional approaches, such as dimensional reduction techniques and computational clustering, although popular, often face reproducibility challenges due to their heavy reliance on inherent data structures, preve… ▽ More Advancements in cytometry technologies have led to a remarkable increase in the number of markers that can be analyzed simultaneously, presenting significant challenges in data analysis. Traditional approaches, such as dimensional reduction techniques and computational clustering, although popular, often face reproducibility challenges due to their heavy reliance on inherent data structures, preventing direct translation of their outputs into gating strategies to be used in downstream experiments. Here we propose the novel Gating Tree methodology, a pathfinding approach that investigates the multidimensional data landscape to unravel group-specific features without the use of dimensional reduction. This method employs novel measures, including enrichment scores and gating entropy, to effectively identify group-specific features within high-dimensional cytometric datasets. Our analysis, applied to both simulated and real cytometric datasets, demonstrates that the Gating Tree not only identifies group-specific features comprehensively but also produces outputs that are immediately usable as gating strategies for unequivocally identifying cell populations. In conclusion, the Gating Tree facilitates a comprehensive analysis of the multidimensional data landscape and provides experimentalists with practical, successive gating strategies that enhance cross-experimental comparisons and downstream analyses such as flow cytometric sorting. △ Less

Submitted 29 June, 2025; v1 submitted 31 October, 2024; originally announced November 2024.

Comments: 10 figures, 30 pages

Constraining the CSM structure and progenitor mass-loss history of interacting supernovae through 3D hydrodynamic modeling: The case of SN 2014C

Authors: S. Orlando, E. Greco, R. Hirai, T. Matsuoka, M. Miceli, S. Nagataki, M. Ono, K. -J. Chen, D. Milisavljevic, D. Patnaude, F. Bocchino, N. Elias-Rosa

Abstract: We investigate SN 2014C using three-dimensional hydrodynamic modeling, focusing on its early interaction with dense circumstellar medium (CSM). Our objective is to uncover the pre-supernova (SN) CSM structure and constrain the progenitor star's mass-loss history prior to core collapse. Our comprehensive model traces the evolution from the progenitor star through the SN event and into the SN remnan… ▽ More We investigate SN 2014C using three-dimensional hydrodynamic modeling, focusing on its early interaction with dense circumstellar medium (CSM). Our objective is to uncover the pre-supernova (SN) CSM structure and constrain the progenitor star's mass-loss history prior to core collapse. Our comprehensive model traces the evolution from the progenitor star through the SN event and into the SN remnant (SNR) phase. We simulate the remnant's expansion over approximately 15 years, incorporating a CSM derived from the progenitor star's outflows through dedicated hydrodynamic simulations. Analysis reveals that the remnant interacted with a dense toroidal nebula extending from $4.3\times 10^{16}\,$cm to $1.5\times 10^{17}$ cm in the equatorial plane, with a thickness of approximately $1.2\times 10^{17}$ cm. The nebula's density peaks at approximately $3\times 10^6\,$cm$^{-3}$ at the inner boundary, gradually decreasing as $\approx r^{-2}$ at greater distances. This nebula formed due to intense mass-loss from the progenitor star between approximately 5000 and 1000 years before collapse. During this period, the maximum mass-loss rate reached about $8\times 10^{-4}\,M_{\odot}\,$yr$^{-1}$, ejecting $\approx 2.5\,M_{\odot}$ of stellar material into the CSM. Our model accurately reproduces Chandra and NuSTAR spectra, including the Fe K line, throughout the remnant's evolution. Notably, the Fe line is self-consistently reproduced, originating from shocked ejecta, with $\approx 0.05\,M_{\odot}$ of pure-Fe ejecta shocked during the remnant-nebula interaction. These findings suggest that the 3D geometry and density distribution of the CSM, as well as the progenitor star's mass-loss history, align with a scenario where the star was stripped through binary interaction, specifically common envelope evolution. △ Less

Submitted 23 October, 2024; originally announced October 2024.

Comments: 43 Pages, 25 Figures, 4 Tables, accepted for publication in The Astrophysical Journal

Coarse-Grained Sense Inventories Based on Semantic Matching between English Dictionaries

Authors: Masato Kikuchi, Masatsugu Ono, Toshioki Soga, Tetsu Tanabe, Tadachika Ozono

Abstract: WordNet is one of the largest handcrafted concept dictionaries visualizing word connections through semantic relationships. It is widely used as a word sense inventory in natural language processing tasks. However, WordNet's fine-grained senses have been criticized for limiting its usability. In this paper, we semantically match sense definitions from Cambridge dictionaries and WordNet and develop… ▽ More WordNet is one of the largest handcrafted concept dictionaries visualizing word connections through semantic relationships. It is widely used as a word sense inventory in natural language processing tasks. However, WordNet's fine-grained senses have been criticized for limiting its usability. In this paper, we semantically match sense definitions from Cambridge dictionaries and WordNet and develop new coarse-grained sense inventories. We verify the effectiveness of our inventories by comparing their semantic coherences with that of Coarse Sense Inventory. The advantages of the proposed inventories include their low dependency on large-scale resources, better aggregation of closely related senses, CEFR-level assignments, and ease of expansion and improvement. △ Less

Submitted 10 September, 2024; originally announced September 2024.

Comments: The 11th International Conference on Advanced Informatics: Concepts, Theory and Applications (ICAICTA 2024)

Isotropy of cosmic rays beyond $10^{20}$ eV favors their heavy mass composition

Authors: Telescope Array Collaboration, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Y. Arai, R. Arimura, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, I. Buckland, B. G. Cheon, M. Chikawa, T. Fujii, K. Fujisue, K. Fujita, R. Fujiwara, M. Fukushima, G. Furlich, N. Globus, R. Gonzalez, W. Hanlon, N. Hayashida, H. He , et al. (118 additional authors not shown)

Abstract: We report an estimation of the injected mass composition of ultra-high energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extra-galactic magnetic fields the resul… ▽ More We report an estimation of the injected mass composition of ultra-high energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extra-galactic magnetic fields the results are consistent with a relatively heavy injected composition at E ~ 10 EeV that becomes lighter up to E ~ 100 EeV, while the composition at E > 100 EeV is very heavy. The latter is true even in the presence of highest experimentally allowed extra-galactic magnetic fields, while the composition at lower energies can be light if a strong EGMF is present. The effect of the uncertainty in the galactic magnetic field on these results is subdominant. △ Less

Submitted 3 July, 2024; v1 submitted 27 June, 2024; originally announced June 2024.

Comments: 8 pages, 3 figures, accepted for publication in PRL

Mass composition of ultra-high energy cosmic rays from distribution of their arrival directions with the Telescope Array

Authors: Telescope Array Collaboration, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Y. Arai, R. Arimura, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, I. Buckland, B. G. Cheon, M. Chikawa, T. Fujii, K. Fujisue, K. Fujita, R. Fujiwara, M. Fukushima, G. Furlich, N. Globus, R. Gonzalez, W. Hanlon, N. Hayashida, H. He , et al. (118 additional authors not shown)

Abstract: We use a new method to estimate the injected mass composition of ultrahigh cosmic rays (UHECRs) at energies higher than 10 EeV. The method is based on comparison of the energy-dependent distribution of cosmic ray arrival directions as measured by the Telescope Array experiment (TA) with that calculated in a given putative model of UHECR under the assumption that sources trace the large-scale struc… ▽ More We use a new method to estimate the injected mass composition of ultrahigh cosmic rays (UHECRs) at energies higher than 10 EeV. The method is based on comparison of the energy-dependent distribution of cosmic ray arrival directions as measured by the Telescope Array experiment (TA) with that calculated in a given putative model of UHECR under the assumption that sources trace the large-scale structure (LSS) of the Universe. As we report in the companion letter, the TA data show large deflections with respect to the LSS which can be explained, assuming small extra-galactic magnetic fields (EGMF), by an intermediate composition changing to a heavy one (iron) in the highest energy bin. Here we show that these results are robust to uncertainties in UHECR injection spectra, the energy scale of the experiment and galactic magnetic fields (GMF). The assumption of weak EGMF, however, strongly affects this interpretation at all but the highest energies E > 100 EeV, where the remarkable isotropy of the data implies a heavy injected composition even in the case of strong EGMF. This result also holds if UHECR sources are as rare as $2 \times 10^{-5}$ Mpc$^{-3}$, that is the conservative lower limit for the source number density. △ Less

Submitted 3 July, 2024; v1 submitted 27 June, 2024; originally announced June 2024.

Comments: 18 pages, 11 figures, accepted for publication in PRD

Photonic topological phase transition induced by material phase transition

Authors: Takahiro Uemura, Yuto Moritake, Taiki Yoda, Hisashi Chiba, Yusuke Tanaka, Masaaki Ono, Eiichi Kuramochi, Masaya Notomi

Abstract: Photonic topological insulators (PTIs) have been proposed as an analogy to topological insulators in electronic systems. In particular, two-dimensional PTIs have gained attention for the integrated circuit applications. However, controlling the topological phase after fabrication is difficult because the photonic topology requires the built-in specific structures. This study experimentally demonst… ▽ More Photonic topological insulators (PTIs) have been proposed as an analogy to topological insulators in electronic systems. In particular, two-dimensional PTIs have gained attention for the integrated circuit applications. However, controlling the topological phase after fabrication is difficult because the photonic topology requires the built-in specific structures. This study experimentally demonstrates the band inversion in two-dimensional PTI induced by the phase transition of deliberately-designed nanopatterns of a phase-change material, Ge2Sb2Te5 (GST), which indicates the first observation of the photonic topological phase transition with changes in the Chern number. This approach allows us to directly alter the topological invariants, which is achieved by symmetry-breaking perturbation through GST nanopatterns with different symmetry from original PTI. The success of our scheme is attributed to the ultrafine lithographic alignment technologies of GST nanopatterns. These results demonstrate to control photonic topological properties in a reconfigurable manner, providing an insight into new possibilities for reconfigurable photonic processing circuits. △ Less

Submitted 12 June, 2024; originally announced June 2024.

Probing Shocked Ejecta in SN 1987A with XRISM-Resolve: the effects of the gate valve closed

Authors: Vincenzo Sapienza, Marco Miceli, Aya Bamba, Salvatore Orlando, Shiu-Hang Lee, Shigehiro Nagataki, Masaomi Ono, Satoru Katsuda, Koji Mori, Makoto Sawada, Yukikatsu Terada, Roberta Giuffrida, Fabrizio Bocchino

Abstract: Supernova (SN) 1987A is widely regarded as an excellent candidate for leveraging the capabilities of the freshly launched XRISM satellite. Recent researches indicate that the X-ray emission from SN 1987A will increasingly originate from its ejecta in the years to come. In a previous study, we thoroughly examined the proficiency of XRISM-Resolve in identifying signatures of shocked ejecta in SN 198… ▽ More Supernova (SN) 1987A is widely regarded as an excellent candidate for leveraging the capabilities of the freshly launched XRISM satellite. Recent researches indicate that the X-ray emission from SN 1987A will increasingly originate from its ejecta in the years to come. In a previous study, we thoroughly examined the proficiency of XRISM-Resolve in identifying signatures of shocked ejecta in SN 1987A, synthesizing the XRISM-Resolve spectrum based on a state-of-the-art magneto-hydrodynamic simulation. However, following the satellite's launch, a technical issue arose with the XRISM instrument's gate valve, which failed to open, thereby affecting observations with the Resolve spectrometer. Here, we update our analysis, reevaluating our diagnostic approach under the assumption that the gate valve remains closed. We find that, even with the reduced instrumental capabilities, it will be possible to pinpoint the ejecta contribution through the study of the line profiles in the XRISM-Resolve spectrum of SN 1987A. △ Less

Submitted 31 May, 2024; originally announced June 2024.

Comments: 4 pages, 1 figure. Updates of the results described in Sapienza et al. 2024 (http://doi.org/10.3847/2041-8213/ad16e3). Submitted for publication in Research Notes of the AAS

ShadowNav: Autonomous Global Localization for Lunar Navigation in Darkness

Authors: Deegan Atha, R. Michael Swan, Abhishek Cauligi, Anne Bettens, Edwin Goh, Dima Kogan, Larry Matthies, Masahiro Ono

Abstract: The ability to determine the pose of a rover in an inertial frame autonomously is a crucial capability necessary for the next generation of surface rover missions on other planetary bodies. Currently, most on-going rover missions utilize ground-in-the-loop interventions to manually correct for drift in the pose estimate and this human supervision bottlenecks the distance over which rovers can oper… ▽ More The ability to determine the pose of a rover in an inertial frame autonomously is a crucial capability necessary for the next generation of surface rover missions on other planetary bodies. Currently, most on-going rover missions utilize ground-in-the-loop interventions to manually correct for drift in the pose estimate and this human supervision bottlenecks the distance over which rovers can operate autonomously and carry out scientific measurements. In this paper, we present ShadowNav, an autonomous approach for global localization on the Moon with an emphasis on driving in darkness and at nighttime. Our approach uses the leading edge of Lunar craters as landmarks and a particle filtering approach is used to associate detected craters with known ones on an offboard map. We discuss the key design decisions in developing the ShadowNav framework for use with a Lunar rover concept equipped with a stereo camera and an external illumination source. Finally, we demonstrate the efficacy of our proposed approach in both a Lunar simulation environment and on data collected during a field test at Cinder Lakes, Arizona. △ Less

Submitted 13 September, 2024; v1 submitted 2 May, 2024; originally announced May 2024.

Comments: accepted for IEEE Transactions on Field Robotics (T-FR)

Journal ref: in IEEE Transactions on Field Robotics, vol. 1, pp. 213-230, 2024

Background Noise Reduction of Attention Map for Weakly Supervised Semantic Segmentation

Authors: Izumi Fujimori, Masaki Oono, Masami Shishibori

Abstract: In weakly-supervised semantic segmentation (WSSS) using only image-level class labels, a problem with CNN-based Class Activation Maps (CAM) is that they tend to activate the most discriminative local regions of objects. On the other hand, methods based on Transformers learn global features but suffer from the issue of background noise contamination. This paper focuses on addressing the issue of ba… ▽ More In weakly-supervised semantic segmentation (WSSS) using only image-level class labels, a problem with CNN-based Class Activation Maps (CAM) is that they tend to activate the most discriminative local regions of objects. On the other hand, methods based on Transformers learn global features but suffer from the issue of background noise contamination. This paper focuses on addressing the issue of background noise in attention weights within the existing WSSS method based on Conformer, known as TransCAM. The proposed method successfully reduces background noise, leading to improved accuracy of pseudo labels. Experimental results demonstrate that our model achieves segmentation performance of 70.5% on the PASCAL VOC 2012 validation data, 71.1% on the test data, and 45.9% on MS COCO 2014 data, outperforming TransCAM in terms of segmentation performance. △ Less

Submitted 8 April, 2024; v1 submitted 4 April, 2024; originally announced April 2024.

Multidimensional Radiation Hydrodynamics Simulations of Supernova 1987A Shock Breakout

Authors: Wun-Yi Chen, Ke-Jung Chen, Masaomi Ono

Abstract: Shock breakout is the first electromagnetic signal from supernovae (SNe), which contains important information on the explosion energy and the size and chemical composition of the progenitor star. This paper presents the first two-dimensional (2D) multi-wavelength radiation hydrodynamics simulations of SN 1987A shock breakout by using the $\texttt{CASTRO}$ code with the opacity table,… ▽ More Shock breakout is the first electromagnetic signal from supernovae (SNe), which contains important information on the explosion energy and the size and chemical composition of the progenitor star. This paper presents the first two-dimensional (2D) multi-wavelength radiation hydrodynamics simulations of SN 1987A shock breakout by using the $\texttt{CASTRO}$ code with the opacity table, $\texttt{OPAL}$, considering eight photon groups from infrared to X-ray. To investigate the impact of the pre-supernova environment of SN 1987A, we consider three possible circumstellar medium (CSM) environments: a steady wind, an eruptive mass loss, and the existence of a companion star. In sum, the resulting breakout light curve has an hour duration and its peak luminosity of $\sim 4\times 10^{46}\,\rm{erg\,s^{-1}}$ then following a decay rate of $\sim 3.5\,\rm{mag\,hour^{-1}}$ in X-ray. The dominant band transits to UV around 3 hours after the initial breakout, and its luminosity has a decay rate of $\sim 1.5\,\rm{mag\,hour^{-1}}$ that agrees well with the observed shock breakout tail. The detailed features of breakout emission are sensitive to the pre-explosion environment. Furthermore, our 2D simulations demonstrate the importance of multidimensional mixing and its impacts on shock dynamics and radiation emission. The mixing emerging from the shock breakout may lead to a global asymmetry of SN ejecta and affect its later supernova remnant formation. △ Less

Submitted 22 September, 2024; v1 submitted 29 February, 2024; originally announced February 2024.

Comments: 33 pages, 35 figures, 3 tables 19-Sep-2024 Accepted by APJ

Probing Shocked Ejecta in SN 1987A: A novel diagnostic approach using XRISM-Resolve

Authors: Vincenzo Sapienza, Marco Miceli, Aya Bamba, Salvatore Orlando, Shiu-Hang Lee, Shigehiro Nagataki, Masaomi Ono, Satoru Katsuda, Koji Mori, Makoto Sawada, Yukikatsu Terada, Roberta Giuffrida, Fabrizio Bocchino

Abstract: Supernova (SN) 1987A is one of the best candidates to exploit the capabilities of the freshly launched XRISM satellite. This celestial object offers the unique opportunity to study the evolution of a SN into a young supernova remnant. To date, the X-ray emission has been dominated by the shocked circumstellar medium (CSM), with no shocked ejecta firmly detected. However, recent studies provide com… ▽ More Supernova (SN) 1987A is one of the best candidates to exploit the capabilities of the freshly launched XRISM satellite. This celestial object offers the unique opportunity to study the evolution of a SN into a young supernova remnant. To date, the X-ray emission has been dominated by the shocked circumstellar medium (CSM), with no shocked ejecta firmly detected. However, recent studies provide compelling evidence that in the forthcoming years the X-ray emission from SN 1987A will increasingly stem from the ejecta. Our aim is to assess the proficiency of XRISM-Resolve high resolution spectrometer in pinpointing signatures of the shocked ejecta in SN 1987A. Taking advantage of a self consistent state-of-art magneto-hydrodynamic simulation that describes the evolution from SN 1987A to its remnant, we synthesized the XRISM-Resolve spectrum of SN 1987A, as it would be collected in the allocated observation during the performance verification phase, which is foreseen for 2024. Our predictions clearly show the leading role of shocked ejecta in shaping the profile of the emission lines. The Doppler broadening associated with the bulk motion along the line of sight of the rapidly expanding ejecta is shown to increase the line widths well above the values observed so far. The quantitative comparison between our synthetic spectra and the XRISM spectra will enable us to establish a strong connection between the broadened line emission and the freshly shocked ejecta. This, in turn, will allow us to retrieve the ejecta dynamics and chemical composition from the X-ray emission. △ Less

Submitted 18 December, 2023; originally announced December 2023.

Comments: 9 pages, 4 figures, 1 table, Accepted for publication in The Astrophysical Journal Letters

High Transmission in 120-degree Sharp Bends of Inversion-symmetric and Inversion-asymmetric Photonic Crystal Waveguides

Authors: Wei Dai, Taiki Yoda, Yuto Moritake, Masaaki Ono, Eiichi Kuramochi, Masaya Notomi

Abstract: Bending loss is one of the serious problems for constructing nanophotonic integrated circuits. Recently, many works reported that valley photonic crystals (VPhCs) enable significantly high transmission via 120-degree sharp bends. However, it is unclear whether the high bend-transmission results directly from the valley-photonic effects, which are based on the breaking of inversion symmetry. In thi… ▽ More Bending loss is one of the serious problems for constructing nanophotonic integrated circuits. Recently, many works reported that valley photonic crystals (VPhCs) enable significantly high transmission via 120-degree sharp bends. However, it is unclear whether the high bend-transmission results directly from the valley-photonic effects, which are based on the breaking of inversion symmetry. In this study, we conduct a series of comparative numerical and experimental investigations of bend-transmission in various triangular PhCs with and without inversion symmetry and reveal that the high bend-transmission is solely determined by the domain-wall configuration and independent of the existence of the inversion symmetry. Preliminary analysis of the polarization distribution indicates that high bend-transmissions are closely related to the appearance of local topological polarization singularities near the bending section. Our work demonstrates that high transmission can be achieved in a much wider family of PhC waveguides, which may provide novel designs for low-loss nanophotonic integrated circuits with enhanced flexibility and a new understanding of the nature of valley-photonics △ Less

Submitted 18 January, 2025; v1 submitted 26 October, 2023; originally announced October 2023.

Comments: 15 pages, 7 figures, and 1 table & Supplementary information (18 pages, 15 figures and 1 table). Submitted to Nature Communication

Journal ref: Nat Commun 16, 796 (2025)

Diagonal tensor algebra and naive liftings

Authors: Saeed Nasseh, Maiko Ono, Yuji Yoshino

Abstract: The notion of naive lifting of DG modules was introduced by the authors in [16,17] for the purpose of studying problems in homological commutative algebra that involve self-vanishing of Ext. Our goal in this paper is to deeply study the naive lifting property using the tensor algebra of the shift of the diagonal ideal (or, diagonal tensor algebra, as is phrased in the title of this paper). Our mai… ▽ More The notion of naive lifting of DG modules was introduced by the authors in [16,17] for the purpose of studying problems in homological commutative algebra that involve self-vanishing of Ext. Our goal in this paper is to deeply study the naive lifting property using the tensor algebra of the shift of the diagonal ideal (or, diagonal tensor algebra, as is phrased in the title of this paper). Our main result provides several characterizations of naive liftability of DG modules under certain Ext vanishing conditions. As an application, we affirmatively answer [19, Question 4.10] under the same assumptions. △ Less

Submitted 11 September, 2023; originally announced September 2023.

Comments: 20 pages

MSC Class: 13A02; 13D07; 13D09; 16E30; 16E45

Synthesizing Event-centric Knowledge Graphs of Daily Activities Using Virtual Space

Authors: Shusaku Egami, Takanori Ugai, Mikiko Oono, Koji Kitamura, Ken Fukuda

Abstract: Artificial intelligence (AI) is expected to be embodied in software agents, robots, and cyber-physical systems that can understand the various contextual information of daily life in the home environment to support human behavior and decision making in various situations. Scene graph and knowledge graph (KG) construction technologies have attracted much attention for knowledge-based embodied quest… ▽ More Artificial intelligence (AI) is expected to be embodied in software agents, robots, and cyber-physical systems that can understand the various contextual information of daily life in the home environment to support human behavior and decision making in various situations. Scene graph and knowledge graph (KG) construction technologies have attracted much attention for knowledge-based embodied question answering meeting this expectation. However, collecting and managing real data on daily activities under various experimental conditions in a physical space are quite costly, and developing AI that understands the intentions and contexts is difficult. In the future, data from both virtual spaces, where conditions can be easily modified, and physical spaces, where conditions are difficult to change, are expected to be combined to analyze daily living activities. However, studies on the KG construction of daily activities using virtual space and their application have yet to progress. The potential and challenges must still be clarified to facilitate AI development for human daily life. Thus, this study proposes the VirtualHome2KG framework to generate synthetic KGs of daily life activities in virtual space. This framework augments both the synthetic video data of daily activities and the contextual semantic data corresponding to the video contents based on the proposed event-centric schema and virtual space simulation results. Therefore, context-aware data can be analyzed, and various applications that have conventionally been difficult to develop due to the insufficient availability of relevant data and semantic information can be developed. We also demonstrate herein the utility and potential of the proposed VirtualHome2KG framework through several use cases, including the analysis of daily activities by querying, embedding, and clustering, and fall risk detection among ... △ Less

Submitted 30 July, 2023; originally announced July 2023.

Comments: 17 pages, 12 figures, and this paper has been accepted by IEEE Access

ACM Class: I.2.4; H.4.2; H.3.3; H.3.1

Journal ref: IEEE Access, Volume 11, pp.23857-23873, 2023

The impact of effective matter mixing based on three-dimensional hydrodynamical models on the molecule formation in the ejecta of SN 1987A

Authors: Masaomi Ono, Takaya Nozawa, Shigehiro Nagataki, Alexandra Kozyreva, Salvatore Orlando, Marco Miceli, Ke-Jung Chen

Abstract: To investigate the impact of matter mixing on the formation of molecules in the ejecta of SN 1987A, time-dependent rate equations for chemical reactions are solved for one-zone and one-dimensional ejecta models of SN 1987A. The latter models are based on the one-dimensional profiles obtained by angle-averaging of the three-dimensional hydrodynamical models (Ono et al. 2020), which effectively refl… ▽ More To investigate the impact of matter mixing on the formation of molecules in the ejecta of SN 1987A, time-dependent rate equations for chemical reactions are solved for one-zone and one-dimensional ejecta models of SN 1987A. The latter models are based on the one-dimensional profiles obtained by angle-averaging of the three-dimensional hydrodynamical models (Ono et al. 2020), which effectively reflect the 3D matter mixing; the impact is demonstrated, for the first time, based on three-dimensional hydrodynamical models. The distributions of initial seed atoms and radioactive $^{56}$Ni influenced by the mixing could affect the formation of molecules. By comparing the calculations for spherical cases and for several specified directions in the bipolar-like explosions in the three-dimensional hydrodynamical models, the impact is discussed. The decay of $^{56}$Ni, practically $^{56}$Co at later phases, could heat the gas and delay the molecule formation. Additionally, Compton electrons produced by the decay could ionize atoms and molecules and could destruct molecules. Several chemical reactions involved with ions such as H$^+$ and He$^+$ could also destruct molecules. The mixing of $^{56}$Ni plays a non-negligible role in both the formation and destruction of molecules through the processes above. The destructive processes of carbon monoxide and silicon monoxide due to the decay of $^{56}$Ni generally reduce the amounts. However, if the molecule formation is sufficiently delayed under a certain condition, the decay of $^{56}$Ni could locally increase the amounts through a sequence of reactions. △ Less

Submitted 2 January, 2024; v1 submitted 4 May, 2023; originally announced May 2023.

Comments: 85 pages, 32 figures, 8 tables; accepted for publication in ApJS

Report number: RIKEN-iTHEMS-Report-24

Investigating Time Evolution of Thermal Emission from the Putative Neutron Star in SN 1987A for 50+ Years

Authors: Akira Dohi, Emanuele Greco, Shigehiro Nagataki, Masaomi Ono, Marco Miceli, Salvatore Orlando, Barbara Olmi

Abstract: Observations collected with the Atacama Large Millimeter/submillimeter Array (ALMA) and analysis of broadband X-ray spectra have recently suggested the presence of a central compact object (CCO) in SN 1987A. However, no direct evidence of the CCO has been found yet. Here we analyze Chandra X-ray observations of SN 1987A collected in 2007 and 2018, and synthesize the 2027 Chandra and 2037 Lynx spec… ▽ More Observations collected with the Atacama Large Millimeter/submillimeter Array (ALMA) and analysis of broadband X-ray spectra have recently suggested the presence of a central compact object (CCO) in SN 1987A. However, no direct evidence of the CCO has been found yet. Here we analyze Chandra X-ray observations of SN 1987A collected in 2007 and 2018, and synthesize the 2027 Chandra and 2037 Lynx spectra of the faint inner region of SN 1987A. We estimate the temporal evolution of the upper limits of the intrinsic luminosity of the putative CCO in three epochs (2018, 2027 and 2037). We find that these upper limits are higher for higher neutron star (NS) kick velocities due to the increased absorption from the surrounding cold ejecta. We compare NS cooling models with both the intrinsic luminosity limits obtained from the X-ray spectra, and the ALMA constraints with the assumption that the observed blob of SN 1987A is primarily heated by thermal emission. We find that the synthetic Lynx spectra are crucial to constrain physical properties of the CCO, which will be confirmed by future observations in the 2040s. We draw our conclusions based on two scenarios, namely the non-detection and detection of NS by Lynx. If the NS is not detected, its kick velocity should be ~700 km/s. Furthermore, the non-detection of the NS would suggest rapid cooling processes around the age of 40 years, implying strong crust superfluidity. Conversely, in the case of NS detection, the mass of the NS envelope must be high. △ Less

Submitted 17 April, 2023; originally announced April 2023.

Comments: 37 pages, 17 figures, 6 tables, accepted for publication in ApJ

Report number: RIKEN-iTHEMS-Report-23

Weighted sum formula for variants of half multiple zeta values

Authors: Hanamichi Kawamura, Takumi Maesaka, Masataka Ono

Abstract: We prove some weighted sum formulas for half multiple zeta values, half finite multiple zeta values, and half symmetric multiple zeta values. The key point of our proof is Dougall's identity for the generalized hypergeometric function ${}_{5}F_{4}$. Similar results for interpolated refined symmetric multiple zeta values and half refined symmetric multiple zeta values are also discussed. We prove some weighted sum formulas for half multiple zeta values, half finite multiple zeta values, and half symmetric multiple zeta values. The key point of our proof is Dougall's identity for the generalized hypergeometric function ${}_{5}F_{4}$. Similar results for interpolated refined symmetric multiple zeta values and half refined symmetric multiple zeta values are also discussed. △ Less

Submitted 6 April, 2023; v1 submitted 27 March, 2023; originally announced March 2023.

Comments: 19 pages

MSC Class: 11M32; 11M35

On the semifree resolutions of DG algebras over the enveloping DG algebras

Authors: Saeed Nasseh, Maiko Ono, Yuji Yoshino

Abstract: The goal of this paper is to construct a semifree resolution for a non-negatively graded strongly commutative DG algebra $B$ over the enveloping DG algebra $B\otimes_AB$, where $A\subseteq B$ is a DG subalgebra and $B$ is semifree over $A$. Our construction of such a semifree resolution uses the notions of reduced bar resolution and tensor algebra of the shift of the diagonal ideal. The goal of this paper is to construct a semifree resolution for a non-negatively graded strongly commutative DG algebra $B$ over the enveloping DG algebra $B\otimes_AB$, where $A\subseteq B$ is a DG subalgebra and $B$ is semifree over $A$. Our construction of such a semifree resolution uses the notions of reduced bar resolution and tensor algebra of the shift of the diagonal ideal. △ Less

Submitted 25 June, 2023; v1 submitted 28 January, 2023; originally announced January 2023.

ShadowNav: Crater-Based Localization for Nighttime and Permanently Shadowed Region Lunar Navigation

Authors: Abhishek Cauligi, R. Michael Swan, Masahiro Ono, Shreyansh Daftry, John Elliott, Larry Matthies, Deegan Atha

Abstract: There has been an increase in interest in missions that drive significantly longer distances per day than what has currently been performed. Further, some of these proposed missions require autonomous driving and absolute localization in darkness. For example, the Endurance A mission proposes to drive 1200km of its total traverse at night. The lack of natural light available during such missions l… ▽ More There has been an increase in interest in missions that drive significantly longer distances per day than what has currently been performed. Further, some of these proposed missions require autonomous driving and absolute localization in darkness. For example, the Endurance A mission proposes to drive 1200km of its total traverse at night. The lack of natural light available during such missions limits what can be used as visual landmarks and the range at which landmarks can be observed. In order for planetary rovers to traverse long ranges, onboard absolute localization is critical to the ability of the rover to maintain its planned trajectory and avoid known hazardous regions. Currently, to accomplish absolute localization, a ground in the loop (GITL) operation is performed wherein a human operator matches local maps or images from onboard with orbital images and maps. This GITL operation limits the distance that can be driven in a day to a few hundred meters, which is the distance that the rover can maintain acceptable localization error via relative methods. Previous work has shown that using craters as landmarks is a promising approach for performing absolute localization on the moon during the day. In this work we present a method of absolute localization that utilizes craters as landmarks and matches detected crater edges on the surface with known craters in orbital maps. We focus on a localization method based on a perception system which has an external illuminator and a stereo camera. We evaluate (1) both monocular and stereo based surface crater edge detection techniques, (2) methods of scoring the crater edge matches for optimal localization, and (3) localization performance on simulated Lunar surface imagery at night. We demonstrate that this technique shows promise for maintaining absolute localization error of less than 10m required for most planetary rover missions. △ Less

Submitted 11 January, 2023; originally announced January 2023.

Comments: IEEE Aerospace Conference 2023

Polarized radio emission unveils the structure of the pre-supernova circumstellar magnetic field and the radio emission in SN1987A

Authors: O. Petruk, V. Beshley, S. Orlando, F. Bocchino, M. Miceli, S. Nagataki, M. Ono, S. Loru, A. Pellizzoni, E. Egron

Abstract: The detected polarized radio emission from remnant of SN1987A opens the possibility to unveil the structure of the pre-supernova magnetic field in the circumstellar medium. Properties derived from direct measurements would be of importance for understanding the progenitor stars and their magnetic fields. As the first step to this goal, we adopted the hydrodynamic data from an elaborated three-dime… ▽ More The detected polarized radio emission from remnant of SN1987A opens the possibility to unveil the structure of the pre-supernova magnetic field in the circumstellar medium. Properties derived from direct measurements would be of importance for understanding the progenitor stars and their magnetic fields. As the first step to this goal, we adopted the hydrodynamic data from an elaborated three-dimensional (3-D) numerical model of SN1987A. We have developed an approximate method for `reconstruction' of 3-D magnetic field structure inside supernova remnant on the `hydrodynamic background'. This method uses the distribution of the magnetic field around the progenitor as the initial condition. With such a 3-D magneto-hydrodynamic model, we have synthesized the polarization maps for a number of SN1987A models and compared them to the observations. In this way, we have tested different initial configurations of the magnetic field as well as a structure of the synchrotron emission in SN987A. We have recovered the observed polarization pattern and we have found that the radial component of the ambient pre-supernova magnetic field should be dominant on the length-scale of the present-day radius of SN1987A. The physical reasons for such a field are discussed. △ Less

Submitted 1 December, 2022; originally announced December 2022.

Comments: 13 pages, 8 figures, accepted in MNRAS

How Population III Supernovae Determined the Properties of the First Galaxies

Authors: Ke-Jung Chen, Ching-Yao Tang, Daniel J. Whalen, Meng-Yuan Ho, Sung-Han Tsai, Po-Sheng Ou, Masaomi Ono

Abstract: Massive Pop III stars can die as energetic supernovae that enrich the early universe with metals and determine the properties of the first galaxies. With masses of about $10^9$ Msun at $z \gtrsim 10$, these galaxies are believed to be the ancestors of the Milky Way. This paper investigates the impact of Pop III supernova remnants (SNRs) from both Salpeter-like and top-heavy initial mass functions… ▽ More Massive Pop III stars can die as energetic supernovae that enrich the early universe with metals and determine the properties of the first galaxies. With masses of about $10^9$ Msun at $z \gtrsim 10$, these galaxies are believed to be the ancestors of the Milky Way. This paper investigates the impact of Pop III supernova remnants (SNRs) from both Salpeter-like and top-heavy initial mass functions (IMFs) on the formation of first galaxies with high-resolution radiation-hydrodynamical simulations with the ENZO code. Our findings indicate that SNRs from a top-heavy Pop III IMF produce more metals, leading to more efficient gas cooling and earlier Pop II star formation in the first galaxies. From a few hundred to a few thousand Pop II stars can form in the central regions of these galaxies. These stars have metallicities of $10^{-3}$ to $10^{-2}$, Zsun, greater than those of extremely metal-poor (EMP) stars. Their mass function follows a power-law distribution with $dN(M_*)/dM_* \propto M_*^α$, where $M_*$ is stellar mass and $α= 2.66 - 5.83$ and is steeper for a top-heavy IMF. We thus find that EMP stars were not typical of most primitive galaxies. △ Less

Submitted 12 February, 2024; v1 submitted 11 November, 2022; originally announced November 2022.

Comments: 14 pages, 9 figures. Accepted for publication in ApJ. arXiv admin note: substantial text overlap with arXiv:2010.02212

Temporal Multimodal Multivariate Learning

Authors: Hyoshin Park, Justice Darko, Niharika Deshpande, Venktesh Pandey, Hui Su, Masahiro Ono, Dedrick Barkely, Larkin Folsom, Derek Posselt, Steve Chien

Abstract: We introduce temporal multimodal multivariate learning, a new family of decision making models that can indirectly learn and transfer online information from simultaneous observations of a probability distribution with more than one peak or more than one outcome variable from one time stage to another. We approximate the posterior by sequentially removing additional uncertainties across different… ▽ More We introduce temporal multimodal multivariate learning, a new family of decision making models that can indirectly learn and transfer online information from simultaneous observations of a probability distribution with more than one peak or more than one outcome variable from one time stage to another. We approximate the posterior by sequentially removing additional uncertainties across different variables and time, based on data-physics driven correlation, to address a broader class of challenging time-dependent decision-making problems under uncertainty. Extensive experiments on real-world datasets ( i.e., urban traffic data and hurricane ensemble forecasting data) demonstrate the superior performance of the proposed targeted decision-making over the state-of-the-art baseline prediction methods across various settings. △ Less

Submitted 14 June, 2022; originally announced June 2022.

Comments: 11 pages, 12 figures, SIGKDD Conference on Knowledge Discovery and Data Mining,

ACM Class: F.4.1

First High-speed Video Camera Observations of a Lightning Flash Associated with a Downward Terrestrial Gamma-ray Flash

Authors: R. U. Abbasi, M. M. F. Saba, J. W. Belz, P. R. Krehbiel, W. Rison, N. Kieu, D. R. da Silva, Dan Rodeheffer, M. A. Stanley, J. Remington, J. Mazich, R. LeVon, K. Smout, A. Petrizze, T. Abu-Zayyad, M. Allen, Y. Arai, R. Arimura, E. Barcikowski, D. R. Bergman, S. A. Blake, I. Buckland, B. G. Cheon, M. Chikawa, T. Fujii , et al. (127 additional authors not shown)

Abstract: In this paper, we present the first high-speed video observation of a cloud-to-ground lightning flash and its associated downward-directed Terrestrial Gamma-ray Flash (TGF). The optical emission of the event was observed by a high-speed video camera running at 40,000 frames per second in conjunction with the Telescope Array Surface Detector, Lightning Mapping Array, interferometer, electric-field… ▽ More In this paper, we present the first high-speed video observation of a cloud-to-ground lightning flash and its associated downward-directed Terrestrial Gamma-ray Flash (TGF). The optical emission of the event was observed by a high-speed video camera running at 40,000 frames per second in conjunction with the Telescope Array Surface Detector, Lightning Mapping Array, interferometer, electric-field fast antenna, and the National Lightning Detection Network. The cloud-to-ground flash associated with the observed TGF was formed by a fast downward leader followed by a very intense return stroke peak current of -154 kA. The TGF occurred while the downward leader was below cloud base, and even when it was halfway in its propagation to ground. The suite of gamma-ray and lightning instruments, timing resolution, and source proximity offer us detailed information and therefore a unique look at the TGF phenomena. △ Less

Submitted 9 August, 2023; v1 submitted 10 May, 2022; originally announced May 2022.

Journal ref: Geophysical Research Letters, 50, e2023GL102958 (2023)

Additional evidence for a pulsar wind nebula in the heart of SN 1987A from multi-epoch X-ray data and MHD modeling

Authors: Emanuele Greco, Marco Miceli, Salvatore Orlando, Barbara Olmi, Fabrizio Bocchino, Shigehiro Nagataki, Lei Sun, Jacco Vink, Vincenzo Sapienza, Masaomi Ono, Akira Dohi, Giovanni Peres

Abstract: Since the day of its explosion, supernova (SN) 1987A has been closely monitored to study its evolution and to detect its central compact relic. In fact, the formation of a neutron star is strongly supported by the detection of neutrinos from the SN. However, besides the detection in the Atacama Large Millimeter/submillimeter Array (ALMA) data of a feature that is compatible with the emission arisi… ▽ More Since the day of its explosion, supernova (SN) 1987A has been closely monitored to study its evolution and to detect its central compact relic. In fact, the formation of a neutron star is strongly supported by the detection of neutrinos from the SN. However, besides the detection in the Atacama Large Millimeter/submillimeter Array (ALMA) data of a feature that is compatible with the emission arising from a proto-pulsar wind nebula (PWN), the only hint for the existence of such elusive compact object is provided by the detection of hard emission in NuSTAR data up to ~ 20 keV. We report on the simultaneous analysis of multi-epoch observations of SN 1987A performed with Chandra, XMM-Newton and NuSTAR. We also compare the observations with a state-of-the-art 3D magnetohydrodynamic (MHD) simulation of SN 1987A. A heavily absorbed power-law, consistent with the emission from a PWN embedded in the heart of SN 1987A, is needed to properly describe the high-energy part of the observed spectra. The spectral parameters of the best-fit power-law are in agreement with the previous estimate, and exclude diffusive shock acceleration as a possible mechanism responsible for the observed non-thermal emission. The information extracted from our analysis are used to infer the physical characteristics of the pulsar and the broad-band emission of its nebula, in agreement with the ALMA data. Analysis of the synthetic spectra also show that, in the near future, the main contribution to Fe K emission line will originate in the outermost shocked ejecta of SN 1987A. △ Less

Submitted 14 April, 2022; originally announced April 2022.

Comments: Accepted for publication in ApJ

Comprehensive Analyses of the Neutrino-Process in the Core-collapsing Supernova

Authors: Heamin Ko, Dukjae Jang, Myung-Ki Cheoun, Motohiko Kusakabe, Hirokazu Sasaki, Xingqun Yao, Toshitaka Kajino, Takehito Hayakawa, Masaomi Ono, Toshihiko Kawano, Grant J. Mathews

Abstract: We investigate the neutrino flavor change effects due to neutrino self-interaction, shock wave propagation as well as matter effect on the neutrino-process of the core-collapsing supernova (CCSN). For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamic model for SN1987A. As a pre-supernova model, we take an updated model adjusted to explain the SN1987A em… ▽ More We investigate the neutrino flavor change effects due to neutrino self-interaction, shock wave propagation as well as matter effect on the neutrino-process of the core-collapsing supernova (CCSN). For the hydrodynamics, we use two models: a simple thermal bomb model and a specified hydrodynamic model for SN1987A. As a pre-supernova model, we take an updated model adjusted to explain the SN1987A employing recent development of the $(n,γ)$ reaction rates for nuclei near the stability line $(A \sim 100)$. As for the neutrino luminosity, we adopt two different models: equivalent neutrino luminosity and non-equivalent luminosity models. The latter is taken from the synthetic analyses of the CCSN simulation data which involved quantitatively the results obtained by various neutrino transport models. Relevant neutrino-induced reaction rates are calculated by a shell model for light nuclei and a quasi-particle random phase approximation model for heavy nuclei. For each model, we present abundances of the light nuclei ($^7$Li, $^7$Be, $^{11}$B and $^{11}$C) and heavy nuclei ($^{92}$Nb, $^{98}$Tc, $^{138}$La and $^{180}$Ta) produced by the neutrino-process. The light nuclei abundances turn out to be sensitive to the Mikheyev-Smirnov-Wolfenstein (MSW) region around O-Ne-Mg region while the heavy nuclei are mainly produced prior to the MSW region. Through the detailed analyses, we find that neutrino self-interaction becomes a key ingredient in addition to the MSW effect for understanding the neutrino-process and the relevant nuclear abundances. The normal mass hierarchy is shown to be more compatible with the meteorite data. Main nuclear reactions for each nucleus are also investigated in detail. △ Less

Submitted 16 August, 2022; v1 submitted 24 March, 2022; originally announced March 2022.

Journal ref: Astrophys. J. 937, 116 (2022)

Lunar Rover Localization Using Craters as Landmarks

Authors: Larry Matthies, Shreyansh Daftry, Scott Tepsuporn, Yang Cheng, Deegan Atha, R. Michael Swan, Sanjna Ravichandar, Masahiro Ono

Abstract: Onboard localization capabilities for planetary rovers to date have used relative navigation, by integrating combinations of wheel odometry, visual odometry, and inertial measurements during each drive to track position relative to the start of each drive. At the end of each drive, a ground-in-the-loop (GITL) interaction is used to get a position update from human operators in a more global refere… ▽ More Onboard localization capabilities for planetary rovers to date have used relative navigation, by integrating combinations of wheel odometry, visual odometry, and inertial measurements during each drive to track position relative to the start of each drive. At the end of each drive, a ground-in-the-loop (GITL) interaction is used to get a position update from human operators in a more global reference frame, by matching images or local maps from onboard the rover to orbital reconnaissance images or maps of a large region around the rover's current position. Autonomous rover drives are limited in distance so that accumulated relative navigation error does not risk the possibility of the rover driving into hazards known from orbital images. However, several rover mission concepts have recently been studied that require much longer drives between GITL cycles, particularly for the Moon. These concepts require greater autonomy to minimize GITL cycles to enable such large range; onboard global localization is a key element of such autonomy. Multiple techniques have been studied in the past for onboard rover global localization, but a satisfactory solution has not yet emerged. For the Moon, the ubiquitous craters offer a new possibility, which involves mapping craters from orbit, then recognizing crater landmarks with cameras and-or a lidar onboard the rover. This approach is applicable everywhere on the Moon, does not require high resolution stereo imaging from orbit as some other approaches do, and has potential to enable position knowledge with order of 5 to 10 m accuracy at all times. This paper describes our technical approach to crater-based lunar rover localization and presents initial results on crater detection using 3D point cloud data from onboard lidar or stereo cameras, as well as using shading cues in monocular onboard imagery. △ Less

Submitted 18 March, 2022; originally announced March 2022.

Comments: IEEE Aerospace Conference, 2022

MLNav: Learning to Safely Navigate on Martian Terrains

Authors: Shreyansh Daftry, Neil Abcouwer, Tyler Del Sesto, Siddarth Venkatraman, Jialin Song, Lucas Igel, Amos Byon, Ugo Rosolia, Yisong Yue, Masahiro Ono

Abstract: We present MLNav, a learning-enhanced path planning framework for safety-critical and resource-limited systems operating in complex environments, such as rovers navigating on Mars. MLNav makes judicious use of machine learning to enhance the efficiency of path planning while fully respecting safety constraints. In particular, the dominant computational cost in such safety-critical settings is runn… ▽ More We present MLNav, a learning-enhanced path planning framework for safety-critical and resource-limited systems operating in complex environments, such as rovers navigating on Mars. MLNav makes judicious use of machine learning to enhance the efficiency of path planning while fully respecting safety constraints. In particular, the dominant computational cost in such safety-critical settings is running a model-based safety checker on the proposed paths. Our learned search heuristic can simultaneously predict the feasibility for all path options in a single run, and the model-based safety checker is only invoked on the top-scoring paths. We validate in high-fidelity simulations using both real Martian terrain data collected by the Perseverance rover, as well as a suite of challenging synthetic terrains. Our experiments show that: (i) compared to the baseline ENav path planner on board the Perserverance rover, MLNav can provide a significant improvement in multiple key metrics, such as a 10x reduction in collision checks when navigating real Martian terrains, despite being trained with synthetic terrains; and (ii) MLNav can successfully navigate highly challenging terrains where the baseline ENav fails to find a feasible path before timing out. △ Less

Submitted 9 March, 2022; originally announced March 2022.

Comments: IEEE Robotics and Automation Letters (RA-L) and ICRA 2022

On the refined Kaneko-Zagier conjecture for general integer indices

Authors: Masataka Ono, Shuji Yamamoto

Abstract: The refined Kaneko-Zagier conjecture claims that the algebras spanned by two kinds of "completed" finite multiple zeta values, called $\hat{A}$- and $\hat{S}$-MZVs, are isomorphic. Recently, Komori defined $\hat{S}$-MZVs of general integer (i.e., not necessarily positive) indices, extending the existing definition for positive indices. In view of the refined Kaneko-Zagier conjecture, Komori's work… ▽ More The refined Kaneko-Zagier conjecture claims that the algebras spanned by two kinds of "completed" finite multiple zeta values, called $\hat{A}$- and $\hat{S}$-MZVs, are isomorphic. Recently, Komori defined $\hat{S}$-MZVs of general integer (i.e., not necessarily positive) indices, extending the existing definition for positive indices. In view of the refined Kaneko-Zagier conjecture, Komori's work suggests that these extended values are closely connected to $\hat{A}$-MZVs of general indices, which can be defined in an obvious way. In this paper, we show that the generalization of the refined Kaneko-Zagier conjecture for general integer indices is actually deduced from the conjecture for positive indices. The key ingredient is an inductive formula for $\hat{A}$-MZVs or $\hat{S}$-MZVs of indices which contain at least one non-positive entry. △ Less

Submitted 14 February, 2022; originally announced February 2022.

Comments: 12 pages

MSC Class: Primary 11M32; Secondary 11M35

Evidence for past interaction with an asymmetric circumstellar shell in the young SNR Cassiopeia A

Authors: S. Orlando, A. Wongwathanarat, H. -T. Janka, M. Miceli, S. Nagataki, M. Ono, F. Bocchino, J. Vink, D. Milisavljevic, D. J. Patnaude, G. Peres

Abstract: Observations of the SNR Cassiopeia A (Cas A) show asymmetries in the reverse shock that cannot be explained by models describing a remnant expanding through a spherically symmetric wind of the progenitor star. We investigate whether a past interaction of Cas A with an asymmetric circumstellar shell can account for the observed asymmetries. We performed 3D MHD simulations that describe the remnant… ▽ More Observations of the SNR Cassiopeia A (Cas A) show asymmetries in the reverse shock that cannot be explained by models describing a remnant expanding through a spherically symmetric wind of the progenitor star. We investigate whether a past interaction of Cas A with an asymmetric circumstellar shell can account for the observed asymmetries. We performed 3D MHD simulations that describe the remnant evolution from the SN to its interaction with a circumstellar shell. The initial conditions are provided by a 3D neutrino-driven SN model whose morphology resembles Cas A. We explored the parameter space of the shell, searching for a set of parameters able to produce reverse shock asymmetries at the age of 350 years analogous to those observed in Cas A. The interaction of the remnant with the shell can produce asymmetries resembling those observed in the reverse shock if the shell was asymmetric with the densest portion in the nearside to the northwest (NW). The reverse shock shows the following asymmetries at the age of Cas A: i) it moves inward in the observer frame in the NW region, while it moves outward in other regions; ii) the geometric center of the reverse shock is offset to the NW from the geometric center of the forward shock; iii) the reverse shock in the NW region has enhanced nonthermal emission because, there, the ejecta enter the reverse shock with a higher velocity (between 4000 and 7000 km/s) than in other regions (below 2000 km/s). The asymmetries observed in the reverse shock of Cas A can be interpreted as signatures of the interaction of the remnant with an asymmetric circumstellar shell that occurred between 180 and 240 years after the SN event. We suggest that the shell was, most likely, the result of a massive eruption from the progenitor star that occurred between $10^4$ and $10^5$ years prior to core-collapse. We estimate a total mass of the shell of the order 2 Msun. △ Less

Submitted 12 August, 2022; v1 submitted 3 February, 2022; originally announced February 2022.

Comments: 20 pages, 11 figures, 2 Tables, 1 interactive graphics. Accepted for publication on A&A, high quality figures will be available on the published paper

Journal ref: A&A 666, A2 (2022)